Manufacture of viscose silk



PATENT OFFICE.

EMILE BRONNERT, OF Mll'LHAUSEN, ALSACE-LORRAINE, FRANCE.

MANUFACTURE OF VISCOSE SILK.

No Drawing.

To all whom it may concern:

Be it known that I, EMILE Bnormnn'r, a citizen of the Republic of France, residing at 1 Qguai du Barrage, in Miilhausen, Alsace- Lorraine, France, have invented certain new and useful Improvements in the Manufacture of Viscose Silk, (for which I have filed application in Germany, filed January 23, 1919; Bel ium,Denn1ark England, Finland, France, etherlands, Italy, Norway Austria, Sweden, Switzerland Spain, dzechoslovakia, Hungary, filed March 22, 1 920; and Poland, filed April 26, 1920,) of which the following is a specification.

This invention relates to a process for the manufacture of very fine threads of viscose silk by precipitation of raw viscose solutions by means of an acid. v

It is well known that in the production of artificial silk threads from viscose, by means of mineral acid, there must correspond to every age of the viscose a definite acid concentration with a definite spinning length and bath temperature.

These observations related at the time to the usual commercial class of silk of about 7-8 deniers. I

Now by means of experiments applicant has found that the degree of fineness .of the produced thread is a function ofthe acid concentration, either possibly because the acid is bound to a base that can be driven out by soda lye, or because it is only partially bound or partly free.

Trials with pure acid (sulfuric acid, hydrochloric acid, etc or with acid that only contains so much salt as to be equal to that which is unavoidably formed by spinningg have given the astonishing result that the conditions here are similar to these prevailing with the use of acid baths containing much salt.

Furthermore there is also the astonishing fact that,.in order to obtain the maximum degree of fineness, acid concentrations can and must be employed which have hitherto been regarded as directly harmful to the tenacity or strength of the threads especially when working with an increased temperature.

Upon the basis of numerous'experiments applicant has found that, on spinning by means of the usual apparatus and with the Specification of Letters Patent.

, Patented Oct. 11, 1921.

Application filed August 30, 1920. Serial No. 406,911.

of the same drawing 01f speed and of the feed quantity of viscose solution corresponding to the deniers required at the time, the concentration of the acid is so selected that the minimum concentration of the acid,

whih gives a faultless spinning with a coarser denier must for a further desired concentration be chosen approximately .inversely proportionated to the square roots of the two thread denier figure."

This law, occurring in using acid alone, is drawn from, the following practical examples: 1 1. Raw viscose of about 8 degrees of ripeness (chlorid of ammonia) is spun in the usual manner with a correspondingly regulated feed of the viscose, for example in sulfuric acid of about 250-gr. per liter, threads of 2 deniers which can easily be wound up being obtained.

2. Raw viscose of about 7 degrees of ripeness (chlorid of ammonium) is spun in the usual'manner with a correspondingly regulated feed of the viscose, for instance in sulfuric acid of about, 350 gr. per liter, threads of about 1 denier being obtained which can be readily wound up.

As a matter of fact, according to the above mentioned example the concentration of the second bath must be calculated according to the formula v inversely as the squares of the acid concentrations-of the baths.

where O zacid concentration of first loath:

'Symbolically represented, we have and by squaring Both sides of the equation we get suitable openings into acoagulating bath consisting of an acid, the concentration of which is proportional to the fineness of the thread desired,

2. The process of roducing'artificial silk threads comprising orcing vlscose through masses" suitable openings into a coagulating bath consisting of anacid, the concentration of which is inversely proportional to the square root-of the fineness of the thread desired, -measured in deniers.

3. In the process of producing artificial silk threads by forcing viscose through suitable openings into a coagulating acid bath, the method of predetermining the acid concentration necessary to produce a thread of a given fineness, which consists in first determining the minimum concentration of the acid which gives a faultless spinning thread of a certain fineness and then varying the concentration of the bath in accordance with the equation In witness whereof, I have hereunto signed my name in the presence of two subscribing witnesses.

Witnesses:

L. R. DE SALIS, N. L. MEINEBERGER.

EMILE 'BRONNERT, t 

